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    <title>Chaining Interceptor</title>
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        <div style="margin: 0px 10px 8px 10px"  class="pagetitle">Chaining Interceptor</div>

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            <div id="ConfluenceContent"><h2 id="ChainingInterceptor-Description">Description</h2><p>An interceptor that copies all the properties of every object in the value stack to the currently executing object,&#160;except for any object that implements <a shape="rect" class="external-link" href="http://struts.apache.org/maven/xwork-core/apidocs/com/opensymphony/xwork2/Unchainable.html">Unchainable</a>. A collection of optional <code>includes</code>&#160;and&#160;<code>excludes</code>&#160;may be provided to control how and which parameters are copied. Only <code>includes</code>&#160;or <code>excludes</code>&#160;may be&#160;specified. Specifying both results in undefined behavior. See the javadocs for <a shape="rect" class="external-link" href="http://struts.apache.org/maven/xwork-core/apidocs/com/opensymphony/xwork2/util/reflection/ReflectionProvider.html#copy(java.lang.Object, java.lang.Object, java.util.Map, java.util.Collection, java.util.Collection)">ReflectionProvider#copy(Object, Object,&#160;java.util.Map, java.util.Collection, java.util.Collection)</a> for more information.</p><div class="confluence-information-macro confluence-information-macro-note"><span class="aui-icon aui-icon-small aui-iconfont-warning confluence-information-macro-icon"></span><div class="confluence-information-macro-body"><p>It is important to remember that this interceptor does nothing if there are no objects already on the stack. This means two things:</p><ol><li>you can safely apply it to all your actions without any worry of adverse affects.</li><li><span style="line-height: 1.4285715;">it is up to you to ensure an object exists in the stack prior to invoking this action. The most typical way this is done </span><span style="line-height: 1.4285715;">is through the use of the &lt;b&gt;chain&lt;/b&gt; result type, which combines with this interceptor to make up the action </span><span style="line-height: 1.4285715;">chaining feature.</span></li></ol></div></div><p>By default Errors, Field errors and Message aren't copied during chaining, to change the behaviour you can specify<span> the below three constants in struts.properties or struts.xml:</span></p><ul><li><span><code>struts.xwork.chaining.copyErrors</code> - set to true to copy Action Errors</span></li><li><span><code>struts.xwork.chaining.copyFieldErrors</code> - set to true to copy Field Errors</span></li><li><span><code>struts.xwork.chaining.copyMessages</code> - set to true to copy Action Messages</span></li></ul><h3 id="ChainingInterceptor-Example:"><span style="line-height: 1.4285715;">Example:</span></h3><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="brush: xml; gutter: false; theme: Default" style="font-size:12px;">&lt;constant name="struts.xwork.chaining.copyErrors" value="true"/&gt;</pre>
</div></div><h2 id="ChainingInterceptor-Parameters">Parameters</h2><ul style="list-style-type: square;"><li><code>excludes</code>&#160;(optional) - the list of parameter names to exclude from copying (all others will be included)</li><li><span style="line-height: 1.4285715;"><code>includes</code>&#160;(optional) - the list of parameter names to include when copying (all others will be excluded)</span></li></ul><h2 id="ChainingInterceptor-ExtendingtheInterceptor">Extending the Interceptor</h2><p>There are no known extension points to this interceptor.</p><h2 id="ChainingInterceptor-Examples">Examples</h2><p>Simple example how to chain two actions</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="brush: xml; gutter: false; theme: Default" style="font-size:12px;">&lt;action name="someAction" class="com.examples.SomeAction"&gt;
    &lt;interceptor-ref name="basicStack"/&gt;
	&lt;result name="success" type="chain"&gt;otherAction&lt;/result&gt;
&lt;/action&gt;

&lt;action name="otherAction" class="com.examples.OtherAction"&gt;
    &lt;interceptor-ref name="chain"/&gt;
	&lt;interceptor-ref name="basicStack"/&gt;
	&lt;result name="success"&gt;good_result.ftl&lt;/result&gt;
&lt;/action&gt;</pre>
</div></div><p>This examples chains two actions but only one property from first action is copied to another</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<pre class="brush: xml; gutter: false; theme: Default" style="font-size:12px;">&lt;action name="someAction" class="com.examples.SomeAction"&gt;
    &lt;interceptor-ref name="basicStack"/&gt;
	&lt;result name="success" type="chain"&gt;otherAction&lt;/result&gt;
&lt;/action&gt;

&lt;action name="otherAction" class="com.examples.OtherAction"&gt;
    &lt;interceptor-ref name="chainStack"&gt;
		&lt;param name="chain.includes"&gt;prop1&lt;/param&gt;
	&lt;/interceptor-ref&gt;
	&lt;result name="success"&gt;good_result.ftl&lt;/result&gt;
&lt;/action&gt;</pre>
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